There's nothing evil about this.* It seems they got the diamond for free, and the people who gave them it did so to advertise.
*If there is something evil about this, it's the racket of the diamond industry. They manipulate the market to artificially raise their price, engage in anti-competitive practices (especially against much cheaper and better synthetic diamonds), insidiously manipulate culture to make men believe they have to pay a lot of money for diamond engagement and wedding rings, and most evil of all: use child and slave labor to mine them.
There's nothing evil about this.* It seems they got the diamond for free, and the people who gave them it did so to advertise.
*If there is something evil about this, it's the racket of the diamond industry. They manipulate the market to artificially raise their price, engage in anti-competitive practices (especially against much cheaper and better synthetic diamonds), insidiously manipulate culture to make men believe they have to pay a lot of money for diamond engagement and wedding rings, and most evil of all: use child and slave labor to mine them.